Sedentary: You don’t exercise and work a desk job.
Light Activity: You have an active job where you are on your feet most of the day (teacher) but you don’t exercise. Or you work a desk job and do a bit of regular exercise.
Moderate Activity: You are on your feet most of the day and you also train moderately. Or maybe you train very hard and work a desk job. Or you could have a very physically taxing job and not exercise.
Very Active: You train hard most days of the week and you are also on your feet most of the day.
Extremely Active: You have a very physically taxing job and you also train most days of the week. Or you train 2x a day.